[TWOOD]

I wasn't fond of like the idea of a sheet metal screw in fiberglass, so I epoxied stainless steel T-nuts to the underside of the holes, with the sleeve of the T-nut inside the hole. T-nuts can be purchased with holes punched in the T-nut flange and that permits the epoxy to "ooze" up through the holes and,I believe, give it could make a stronger bond.
I have also had good success using sheet metal step drills for making holes in fiberglass. Beats step drilling with individual drill bits.

Oh,... yeah. I forgot to mention, that the reason I liked using T-nuts is that the sheet metal screws can then replaced with machine screws. Then they can be removed and reinstalled al much as you wish and not eventually produce "a loose screw in a sloppy hole" situation.